# Bug Report: Vietnamese Input Not Working in Claude Code CLI

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

📋 Issue Summary

Vietnamese language input is broken when typing in Claude Code CLI, despite working correctly in regular terminal sessions.

🔴 Environment

• OS: macOS 15.1 (Darwin 25.1.0)
• Terminal: iTerm2
• Shell: zsh
• Locale: en_US.UTF-8 (properly configured)
• Input Method:
• ✅ Tested with macOS built-in Vietnamese input
• ✅ Tested with third-party Vietnamese IME (GoTiengViet/EVKey)
• ❌ Both FAIL in Claude Code CLI

🐛 Steps to Reproduce

1. Launch Claude Code CLI in iTerm2
2. Switch to Vietnamese input method (either macOS built-in or third-party)
3. Try to type Vietnamese text with diacritics (e.g., "xin chào", "cảm ơn")
4. Observe broken/garbled characters

✅ Expected Behavior

Vietnamese text should be displayed correctly with proper diacritics, just like in regular terminal sessions.

❌ Actual Behavior

Vietnamese characters are:

• Not displayed correctly
• Diacritics are broken or misplaced
• Input appears garbled

🔍 Additional Context

What Works

• ✅ Vietnamese input works perfectly in regular terminal (same iTerm2 window)
• ✅ Vietnamese output/display works (can see Vietnamese text from commands)
• ✅ Locale is properly set to UTF-8
• ✅ Terminal encoding is UTF-8
• ✅ .inputrc is configured for UTF-8 input

What Doesn't Work

• ❌ Vietnamese input ONLY fails when typing in Claude Code CLI prompt
• ❌ Affects both composition-based IME and direct input

Technical Details

# Locale configuration (confirmed working)
$ locale
LANG="en_US.UTF-8"
LC_ALL="en_US.UTF-8"

# .inputrc configuration (confirmed working)
set input-meta on
set output-meta on
set convert-meta off

💡 Suspected Root Cause

Claude Code CLI appears to use custom input handling (not standard readline) that doesn't properly handle:

1. IME composition events for Vietnamese
2. Unicode combining characters (diacritics)
3. Multi-byte UTF-8 input sequences

🙏 Requested Fix

Please add proper support for:

• Vietnamese IME (both macOS built-in and third-party)
• Composition events for languages with diacritics
• Multi-byte UTF-8 character input

📊 Impact

This affects ALL users in Vietnam and Vietnamese speakers worldwide who need to communicate in their native language when using Claude Code.

🔗 Related Issues

(Search for similar issues with other languages: Chinese, Japanese, Korean, Thai, etc.)

---

Priority: High - Affects entire Vietnamese user base
Category: Input Handling / Internationalization (i18n)

What Should Happen?

Bug Report: Vietnamese Input Not Working in Claude Code CLI

📋 Issue Summary

Vietnamese language input is broken when typing in Claude Code CLI, despite working correctly in regular terminal sessions.

🔴 Environment

• OS: macOS 15.1 (Darwin 25.1.0)
• Terminal: iTerm2
• Shell: zsh
• Locale: en_US.UTF-8 (properly configured)
• Input Method:
• ✅ Tested with macOS built-in Vietnamese input
• ✅ Tested with third-party Vietnamese IME (GoTiengViet/EVKey)
• ❌ Both FAIL in Claude Code CLI

🐛 Steps to Reproduce

1. Launch Claude Code CLI in iTerm2
2. Switch to Vietnamese input method (either macOS built-in or third-party)
3. Try to type Vietnamese text with diacritics (e.g., "xin chào", "cảm ơn")
4. Observe broken/garbled characters

✅ Expected Behavior

Vietnamese text should be displayed correctly with proper diacritics, just like in regular terminal sessions.

❌ Actual Behavior

Vietnamese characters are:

• Not displayed correctly
• Diacritics are broken or misplaced
• Input appears garbled

🔍 Additional Context

What Works

• ✅ Vietnamese input works perfectly in regular terminal (same iTerm2 window)
• ✅ Vietnamese output/display works (can see Vietnamese text from commands)
• ✅ Locale is properly set to UTF-8
• ✅ Terminal encoding is UTF-8
• ✅ .inputrc is configured for UTF-8 input

What Doesn't Work

• ❌ Vietnamese input ONLY fails when typing in Claude Code CLI prompt
• ❌ Affects both composition-based IME and direct input

Technical Details

# Locale configuration (confirmed working)
$ locale
LANG="en_US.UTF-8"
LC_ALL="en_US.UTF-8"

# .inputrc configuration (confirmed working)
set input-meta on
set output-meta on
set convert-meta off

💡 Suspected Root Cause

Claude Code CLI appears to use custom input handling (not standard readline) that doesn't properly handle:

1. IME composition events for Vietnamese
2. Unicode combining characters (diacritics)
3. Multi-byte UTF-8 input sequences

🙏 Requested Fix

Please add proper support for:

• Vietnamese IME (both macOS built-in and third-party)
• Composition events for languages with diacritics
• Multi-byte UTF-8 character input

📊 Impact

This affects ALL users in Vietnam and Vietnamese speakers worldwide who need to communicate in their native language when using Claude Code.

🔗 Related Issues

(Search for similar issues with other languages: Chinese, Japanese, Korean, Thai, etc.)

---

Priority: High - Affects entire Vietnamese user base
Category: Input Handling / Internationalization (i18n)

Error Messages/Logs

# Bug Report: Vietnamese Input Not Working in Claude Code CLI

## 📋 Issue Summary
Vietnamese language input is broken when typing in Claude Code CLI, despite working correctly in regular terminal sessions.

## 🔴 Environment
- **OS**: macOS 15.1 (Darwin 25.1.0)
- **Terminal**: iTerm2
- **Shell**: zsh
- **Locale**: en_US.UTF-8 (properly configured)
- **Input Method**:
  - ✅ Tested with macOS built-in Vietnamese input
  - ✅ Tested with third-party Vietnamese IME (GoTiengViet/EVKey)
  - ❌ Both FAIL in Claude Code CLI

## 🐛 Steps to Reproduce
1. Launch Claude Code CLI in iTerm2
2. Switch to Vietnamese input method (either macOS built-in or third-party)
3. Try to type Vietnamese text with diacritics (e.g., "xin chào", "cảm ơn")
4. Observe broken/garbled characters

## ✅ Expected Behavior
Vietnamese text should be displayed correctly with proper diacritics, just like in regular terminal sessions.

## ❌ Actual Behavior
Vietnamese characters are:
- Not displayed correctly
- Diacritics are broken or misplaced
- Input appears garbled

## 🔍 Additional Context

### What Works
- ✅ Vietnamese input works perfectly in **regular terminal** (same iTerm2 window)
- ✅ Vietnamese output/display works (can see Vietnamese text from commands)
- ✅ Locale is properly set to UTF-8
- ✅ Terminal encoding is UTF-8
- ✅ `.inputrc` is configured for UTF-8 input

### What Doesn't Work
- ❌ Vietnamese input **ONLY fails when typing in Claude Code CLI prompt**
- ❌ Affects both composition-based IME and direct input

### Technical Details

# Locale configuration (confirmed working)
$ locale
LANG="en_US.UTF-8"
LC_ALL="en_US.UTF-8"

# .inputrc configuration (confirmed working)
set input-meta on
set output-meta on
set convert-meta off


## 💡 Suspected Root Cause
Claude Code CLI appears to use custom input handling (not standard readline) that doesn't properly handle:
1. IME composition events for Vietnamese
2. Unicode combining characters (diacritics)
3. Multi-byte UTF-8 input sequences

## 🙏 Requested Fix
Please add proper support for:
- Vietnamese IME (both macOS built-in and third-party)
- Composition events for languages with diacritics
- Multi-byte UTF-8 character input

## 📊 Impact
This affects ALL users in Vietnam and Vietnamese speakers worldwide who need to communicate in their native language when using Claude Code.

## 🔗 Related Issues
(Search for similar issues with other languages: Chinese, Japanese, Korean, Thai, etc.)

---

**Priority**: High - Affects entire Vietnamese user base
**Category**: Input Handling / Internationalization (i18n)

Steps to Reproduce

Bug Report: Vietnamese Input Not Working in Claude Code CLI

📋 Issue Summary

Vietnamese language input is broken when typing in Claude Code CLI, despite working correctly in regular terminal sessions.

🔴 Environment

• OS: macOS 15.1 (Darwin 25.1.0)
• Terminal: iTerm2
• Shell: zsh
• Locale: en_US.UTF-8 (properly configured)
• Input Method:
• ✅ Tested with macOS built-in Vietnamese input
• ✅ Tested with third-party Vietnamese IME (GoTiengViet/EVKey)
• ❌ Both FAIL in Claude Code CLI

🐛 Steps to Reproduce

1. Launch Claude Code CLI in iTerm2
2. Switch to Vietnamese input method (either macOS built-in or third-party)
3. Try to type Vietnamese text with diacritics (e.g., "xin chào", "cảm ơn")
4. Observe broken/garbled characters

✅ Expected Behavior

Vietnamese text should be displayed correctly with proper diacritics, just like in regular terminal sessions.

❌ Actual Behavior

Vietnamese characters are:

• Not displayed correctly
• Diacritics are broken or misplaced
• Input appears garbled

🔍 Additional Context

What Works

• ✅ Vietnamese input works perfectly in regular terminal (same iTerm2 window)
• ✅ Vietnamese output/display works (can see Vietnamese text from commands)
• ✅ Locale is properly set to UTF-8
• ✅ Terminal encoding is UTF-8
• ✅ .inputrc is configured for UTF-8 input

What Doesn't Work

• ❌ Vietnamese input ONLY fails when typing in Claude Code CLI prompt
• ❌ Affects both composition-based IME and direct input

Technical Details

# Locale configuration (confirmed working)
$ locale
LANG="en_US.UTF-8"
LC_ALL="en_US.UTF-8"

# .inputrc configuration (confirmed working)
set input-meta on
set output-meta on
set convert-meta off

💡 Suspected Root Cause

Claude Code CLI appears to use custom input handling (not standard readline) that doesn't properly handle:

1. IME composition events for Vietnamese
2. Unicode combining characters (diacritics)
3. Multi-byte UTF-8 input sequences

🙏 Requested Fix

Please add proper support for:

• Vietnamese IME (both macOS built-in and third-party)
• Composition events for languages with diacritics
• Multi-byte UTF-8 character input

📊 Impact

This affects ALL users in Vietnam and Vietnamese speakers worldwide who need to communicate in their native language when using Claude Code.

🔗 Related Issues

(Search for similar issues with other languages: Chinese, Japanese, Korean, Thai, etc.)

---

Priority: High - Affects entire Vietnamese user base
Category: Input Handling / Internationalization (i18n)

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.27 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Bug Report: Vietnamese Input Not Working in Claude Code CLI

📋 Issue Summary

Vietnamese language input is broken when typing in Claude Code CLI, despite working correctly in regular terminal sessions.

🔴 Environment

• OS: macOS 15.1 (Darwin 25.1.0)
• Terminal: iTerm2
• Shell: zsh
• Locale: en_US.UTF-8 (properly configured)
• Input Method:
• ✅ Tested with macOS built-in Vietnamese input
• ✅ Tested with third-party Vietnamese IME (GoTiengViet/EVKey)
• ❌ Both FAIL in Claude Code CLI

🐛 Steps to Reproduce

1. Launch Claude Code CLI in iTerm2
2. Switch to Vietnamese input method (either macOS built-in or third-party)
3. Try to type Vietnamese text with diacritics (e.g., "xin chào", "cảm ơn")
4. Observe broken/garbled characters

✅ Expected Behavior

Vietnamese text should be displayed correctly with proper diacritics, just like in regular terminal sessions.

❌ Actual Behavior

Vietnamese characters are:

• Not displayed correctly
• Diacritics are broken or misplaced
• Input appears garbled

🔍 Additional Context

What Works

• ✅ Vietnamese input works perfectly in regular terminal (same iTerm2 window)
• ✅ Vietnamese output/display works (can see Vietnamese text from commands)
• ✅ Locale is properly set to UTF-8
• ✅ Terminal encoding is UTF-8
• ✅ .inputrc is configured for UTF-8 input

What Doesn't Work

• ❌ Vietnamese input ONLY fails when typing in Claude Code CLI prompt
• ❌ Affects both composition-based IME and direct input

Technical Details

# Locale configuration (confirmed working)
$ locale
LANG="en_US.UTF-8"
LC_ALL="en_US.UTF-8"

# .inputrc configuration (confirmed working)
set input-meta on
set output-meta on
set convert-meta off

💡 Suspected Root Cause

Claude Code CLI appears to use custom input handling (not standard readline) that doesn't properly handle:

1. IME composition events for Vietnamese
2. Unicode combining characters (diacritics)
3. Multi-byte UTF-8 input sequences

🙏 Requested Fix

Please add proper support for:

• Vietnamese IME (both macOS built-in and third-party)
• Composition events for languages with diacritics
• Multi-byte UTF-8 character input

📊 Impact

This affects ALL users in Vietnam and Vietnamese speakers worldwide who need to communicate in their native language when using Claude Code.

🔗 Related Issues

(Search for similar issues with other languages: Chinese, Japanese, Korean, Thai, etc.)

---

Priority: High - Affects entire Vietnamese user base
Category: Input Handling / Internationalization (i18n)